1. Field of the Invention
This invention relates to a control circuit for an electromagnet with two coils, namely the first coil energized on call and the second coil energized on hold, this circuit comprising a DC power source to power the coils and a first switch and a second switch associated with the call coil and the hold coil respectively to control passage of current.
2. Discussion of the Background
Patent DE-21 28 651 describes a control circuit for an electromagnet with two coils. In the call phase, which lasts for a duration determined by the charge in a capacitance at a level determined by a Zener diode, the two coils are powered to provide the energy necessary to close the electromagnet. Only one of the coils is powered continuously in the hold phase. But this control circuit has the disadvantage that it needs an energy source capable of supplying the call to both coils at the same time.
The purpose of this invention is to obtain a low level energy source, for example similar to call and hold, and to simplify the control circuit necessary for this purpose.